"Our forces are advancing toward the government complex in the centre of Ramadi. The fighting is in the neighbourhoods around the complex, with support from the air force," Sabah al-Numani, spokesman for the counter-terrorism units, told Reuters.

"The city will be cleared in the coming 72 hours," the spokesman told AFP.

Earlier this month, there were fears that thousands of civilians stranded in Ramadi under the control of the Islamic State could be used as human shields as the Iraqi troops advanced.

Ramadi, the capital of the Anbar province in western Iraq, fell to Isis militants in May -- a humiliating defeat for the Iraqi armed forces.

Last month, Iraqi troops surrounded Ramadi and cut off supply lines to the Isis-held area.